As President Obama campaigns in the union-rich territory of Ohio & Pennsylvania, one demographic shift poses a problem for his re-election prospects. Unionized labor now makes up the smallest percentage of the American workforce in 60 years. One-third of American workers belonged to unions in 1945, today it’s less than 14%.

Adding to labor’s woes, this year, unions took some huge hits. The recall election results in Wisconsin and last week’s Supreme Court ruling that bars unions from using dues to pay for political campaigns without prior approval have dealt a double blow to big labor.